The Firefox Beta Version Coexist Perfectly with the Eventual Others Firefox/IceWeasel Installations without Making Any Troubles, this Meaning that an Unique Firefox Base Environment will be Shared between All the Firefox/Iceweasel Versions on the System.

To Make Easier the Visualization of the Entire Process I have Inserted the Essentials Screenshots of the Installation.

Inside the Instructions you will Find also a Link to How-to Create a Launcher for Firefox Browser on Debian Xfce Desktop.